MegaSTE Repair Continued - Video Noise

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geogeo_28
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Re: MegaSTE Repair Continued - Video Noise

Post by geogeo_28 » Thu Jan 07, 2021 9:16 am

Moving around the 32MHz wire as far away as possible of the video signal did nothing.

displaced
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Re: MegaSTE Repair Continued - Video Noise

Post by displaced » Thu Jan 07, 2021 3:18 pm

So just to wrap up from my side:

Have swapped back to the old PSU and the noise has immediately returned. Have ordered exxos’s recap kit for my model PSU, and I’ll keep the Meanwell as a nice multi-volt test supply. I’ve got a bare STE board I can use it on for tinkering.

Thanks all for your help - I should’ve just recapped the damn thing straight away, but I got swayed by its apparently decent output and the good rep that the MSTE’s PSU has!
A bunch of Ataris and others:
Atari XEGS with RGB mod - STFM - Portfolio - Lynx Mk1 with McWill display - Mega STE - Falcon030 - Jaguar
Commodore VIC-20 CR with ClearVideo - CDTV (Wicher 8MB+IDE)
Acorn Electron - Archimedes A3020

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rubber_jonnie
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Re: MegaSTE Repair Continued - Video Noise

Post by rubber_jonnie » Thu Jan 07, 2021 3:22 pm

displaced wrote:
Thu Jan 07, 2021 3:18 pm
So just to wrap up from my side:

Have swapped back to the old PSU and the noise has immediately returned. Have ordered exxos’s recap kit for my model PSU, and I’ll keep the Meanwell as a nice multi-volt test supply. I’ve got a bare STE board I can use it on for tinkering.

Thanks all for your help - I should’ve just recapped the damn thing straight away, but I got swayed by its apparently decent output and the good rep that the MSTE’s PSU has!
PSUs are usually worth recapping from the off, though the rest is normally OK.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

displaced
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Re: MegaSTE Repair Continued - Video Noise

Post by displaced » Thu Jan 07, 2021 3:46 pm

Yeah - don’t know why I didn’t just go for it. Always seems like a big job for amateurs like me. But I’ve done it once before on an Archimedes, and have replaced caps elsewhere with success. And PSU caps are usually nice and chunky on not especially dense PCBs - so not technically difficult, just needs a good amount of care!
A bunch of Ataris and others:
Atari XEGS with RGB mod - STFM - Portfolio - Lynx Mk1 with McWill display - Mega STE - Falcon030 - Jaguar
Commodore VIC-20 CR with ClearVideo - CDTV (Wicher 8MB+IDE)
Acorn Electron - Archimedes A3020

geogeo_28
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Re: MegaSTE Repair Continued - Video Noise

Post by geogeo_28 » Thu Jan 07, 2021 5:54 pm

I guess I will try an other PSU and see if this has an impact on the noise.

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Re: MegaSTE Repair Continued - Video Noise

Post by exxos » Thu Jan 07, 2021 5:58 pm

geogeo_28 wrote:
Thu Jan 07, 2021 5:54 pm
I guess I will try an other PSU and see if this has an impact on the noise.
If your using my PSU then it has like x10 less noise than original ones, so it wouldn't make any sense if a different PSU solved the problem.
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
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geogeo_28
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Re: MegaSTE Repair Continued - Video Noise

Post by geogeo_28 » Thu Jan 07, 2021 10:54 pm

As expected, switching to the original PSU did literally nothing.
I guess I have to take a closer look to the video circuit. :/

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Re: MegaSTE Repair Continued - Video Noise

Post by exxos » Thu Jan 07, 2021 10:57 pm

geogeo_28 wrote:
Thu Jan 07, 2021 10:54 pm
As expected, switching to the original PSU did literally nothing.
I guess I have to take a closer look to the video circuit. :/
I don't remember if you have done this fix.. it may help on a STE anyway with your issue.. :shrug:

https://www.exxoshost.co.uk/atari/last/ ... /index.htm
https://www.exxoshost.co.uk/atari/ All my hardware guides - mods - games - STOS
https://www.exxoshost.co.uk/atari/store2/ - All my hardware mods for sale - Please help support by making a purchase.

geogeo_28
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Re: MegaSTE Repair Continued - Video Noise

Post by geogeo_28 » Thu Jan 07, 2021 11:56 pm

Yup I did this fix. It removes the ghosting but not the noisy vertical lines.

geogeo_28
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Re: MegaSTE Repair Continued - Video Noise

Post by geogeo_28 » Sun Jan 10, 2021 1:55 am

Looking more into this issue. The white lines now starts to be visible at NTSC 60 Hz.
I suspect U401 C301712-001 is failing.
Unfortunately, I don't have a spare part to verify this hyptohesis quickly. :/

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